1. Field of the Invention
This invention relates to a high-speed charge transport material, production method thereof, photoelectric conversion device and electroluminescence device.
2. Description of the Prior Art
Since high-speed transfer of a hole which is a positive charge in a state called a columnar phase of a triphenylene compound which is one of discotic liquid crystals was reported, charge transportability and photoconductivity of a discotic liquid crystal have been receiving attention. In general, a degree of charge transfer of a photoconductive material is reported to be about 100 to 0.1 cm2xc2x7Vxe2x88x921xc2x7Sxe2x88x921 in a semiconductor or organic crystal which is said to have high-speed charge transfer. However, a degree of charge transfer that can be achieved in a general organic compound polycrystal or polymer is only about 10xe2x88x925 to 10xe2x88x926 cm2xc2x7Vxe2x88x921xc2x7Sxe2x88x921. It is very difficult to obtain a high quality organic crystal material which is necessary to attain practical performance. Meanwhile, a semiconductor is considered to be inappropriate for obtaining a large photocurrent. From these viewpoints, merits can be expected from application of a discotic liquid crystal whose molecular alignment is easy to control by an external field to an organic photoconductor.
However, even if a compound exhibits liquid crystallinity, it exhibits a liquid crystal state only within a certain temperature range and switches to another state once it falls outside the range, thereby making high-speed charge transport impossible from then on. Further, the discotic liquid crystal needs to be heated to exhibit liquid crystallinity, which has limited its applications.
An object of the present invention is to provide a novel high-speed charge transport material.
Another object of the present invention is to provide a method for producing the high-speed charge transport material of the present invention.
Still another object of the present invention is to provide a photoelectric conversion device and an electroluminescence device having a layer composed of the high-speed charge transport material of the present invention.
Other objects and advantages of the present invention will be apparent from the following description.
According to the present invention, firstly, the above objects and advantages of the present invention are achieved by a high-speed charge transport material which comprises a polymer of a liquid crystal material represented by the following formula (1): 
wherein R1 to R6 each are independently a group represented by the following formula (2): 
wherein m is a number of 1 to 15, or a group represented by the following formula (3): 
wherein X is a hydrogen atom or methyl group, and n is a number of 1 to 15, with the proviso that at least one of R1 to R6 is a group represented by the formula (3).
Secondly, the above objects and advantages of the present invention are achieved by a method for preparing a high-speed charge transport material, which comprises irradiating a liquid crystal material represented by the above formula (1) with light between substrates each having an electrode and a liquid crystal alignment film to be polymerized there between.
Thirdly, the above objects and advantages of the present invention are achieved by a method for preparing a high-speed charge transport material, which comprises forming a coating having a liquid crystal material represented by the above formula (1) on a substrate having an electrode and a liquid crystal alignment film and irradiating the coating with light.
Fourthly, the above objects and advantages of the present invention are achieved by a photoelectric conversion device having a layer composed of the high-speed charge transport material of the present invention.
Fifthly, the above objects and advantages of the present invention are achieved by an electroluminescence device having a layer composed of the high-speed charge transport material of the present invention.